A Development of Appearance Inspection System for Root Pass Welds of Small Caliber Pipes by Composing Images

It is often difficult to grasp clearly an entire view from partial images of welds (circumferential joint) of inside of small caliber (about 50-300 mm) pipe or tube by industrial endoscopes because of their narrow sight. In this study, an effective system which helps inspect welds of inside of pipes or tubes accurately and immediately by composing panoramic views from their partial images is proposed. The partial images of inside of pipes or tubes were taken with the instrument with built-in CCD camera which was developed in this study. The partial images were composed using the overlapping image data. If geometric distortions exist on images, it is impossible to compose those by reason of the disagreement of overlapping areas, so geometric distortions were corrected as preprocessing. As a result, it is possible to get complete panoramic views of welds of inside of small caliber pipes or tubes automatically. Quality of pictures and operating time reaches a practical level.